Farrell was kind of an inscrutable, lantern-jawed sphinx.
The way he 'handled' the Pedroia/Machado and Price/Eckersley episodes reflected badly on his management skills and had a lot to do with his demise, I think.
FWIW I don't know if anyone else read this, but Pete Abraham reported that one of those 'highly placed sources' told him he witnessed Farrell and DD having quite a heated shouting match about the Pedroia/Machado thing. That's never good for your job security.
Anyway I think kudos are due to DD for the Cora hiring. He got the right guy and he did it in a quick and decisive fashion.